Conventional, glulam wood beams manufacturing are usually manufactured with perfectly squared wood planks corresponding to the width of the desired beam less the wood necessary to plane down the beam so as to obtain perfectly smooth surfaces,
The planing down step is often necessary in view of the fact that the glulam beams can be used as decorating elements as well as structural elements. This double use of glulam beans requires that the surface be exempt of any defects such as the presence of flash on the planks.
On the other hand, an optimum exploitation of forest resources requires that saw mills exact as much squad planks as possible. This objective is particularly difficult to reach when the trees are of small diameter. In this case, the proportion of planks with bark can be important since the diameter of the tree is sometimes insufficient to provide planks of standard dimensions to produce perfectly squared surfaces. However, this type of tree with small trunk diameter, constitutes an important stock of resources of coniferous trees in the subpolar circle in the northern hemisphere. The mechanical resistance of this type of wood is however very good due to the slow growth of the trees which produces a width of high densities and furthermore, is type of wood usually is devoided of large timber knots which can comprimise the mechanical resistance.
Furthermore, the planks with greater width generally used in the preparation of glulam wood beams are made with trunks exhibiting large diameter and they have the tendency to change shape upon drying. This property renders the glueing of the planks difficult. This property renders the glueing of the plank difficult by eating tensions within the beams.
Due to the difficulty to extract planks of sufficient width and exempt of a flash, the above mentioned northern forest resource has been neglected up to now for the manufacturing of plank for the use in glulam wood beams.
The instant invention overcomes the limitation of the prior art by providing a beam and a method of making beams using plank obtained from trees having small trunk diameters.
The instant instant invention provides a wood beam composed of rectangular strips, said strips comprising planks of identical length and having a width substantially smaller than the desired width of the beam, said beam being characterized by the presence of two strips forming the top and the bottom of said beam and a central part comprising either planks or strips, said beam being further characterized by the presence of flash in the interior and by the top, bottom and sides external surfaces being essentially plane.
In an other embodiment there is further provided wood beam composed of rectangular strips, said strips comprising planks of identical length and having a width substantially smaller than the desired width of the beam, said plank being characterized by having two longitudinal plane surfaces substantially parallel constituting the top and the bottom of said plank and having two longitudinal plane surfaces constituting the sides of said planks, the sides being substantially perpendicular to the top surface and the bottom surface, the bottom surface intersecting at a right angle each of the two sides, the top surface being linked to the sides by intersecting said sides at right angles or by the natural curvature of the from which the plank is obtained thus forming flash, said strips being formed by two or more planks adhered by their sides thus forming lateral joints and in such a way that the bottom of the planks form a uniform plane surface and that the sides of the two planks at the lateral ends of the strips, non adjacent to another plank, intersect the top surface and the bottom surface at a right angle, the beam being formed by the assembly and reciprocal adherence of the strips, said beam being characterized by the presence in its interior of planks at least some of which exhibiting flash, said beam being also characterized by a top and a bottom each composed by a strip the bottom of which constituting the exterior of the beam, the strips included between the top strip and the bottom strip forming a central part, said beam being also characterized by two sides having a plane surface perpendicular to the top and bottom of the beam.
The instant invention either provides a method for making the beam according said method comprising the steps of:
obtaining planks having two longitudinal plane surfaces substantially parallel constituting the top and the bottom of said planks and having two longitudinal plane surfaces constituting the sides of said planks, the sides being substantially perpendicular to the top and the bottom surface, the bottom surface making a right angle with each of the two sides, the top surface being linked to the sides by either a right angle or the natural curvature of the trunk from which the plank is obtained thus forming flash; drying the planks to obtain a hydrometric degree compatible with the application of art adhesive; sorting the planks to eliminate those that do not conform with pre-established selection criteria selected from general geometry, absence of timber knots effecting the mechanical resistance of the planks and mechanical resistance properties; treating the sides of the planks to optimize the efficiency of a selected adhesive; selecting the planks sorted according to their width to assemble the strips having a length corresponding to the desired length of the beam; applying the adhesive on said sides of the planks and placing the planks side by side in such a way that the sides are in reciprocal contact and that the bottom of the planks form a plane surface to constitute strips having a width equal to or greater than the desired width of the beam and applying a lateral pressure to optimize adhesion of the plank; joining the strips by their ends to form finger joints; applying an adhesive on the top surface of the strips; and assembling the strips to form a beam having the desired dimensions and applying pressure to optimize the adhesion of she strips.
There is further provided a method in which the planks in the strips differ in their width and are assembled in panels according to a repetitive pattern relative to their width, said panels being cut along the longitudinal axis of the planks to obtain strips of desired width, the cutting being made such that the sides of the strips intersect the bottom and top surfaces of said planks at a right angle and that said sides are constituted essentially of the duramen of the wood.